Cancer is the second leading cause of death, resulting in one out of every four deaths, in the United States. In 1997, the estimated total number of new diagnoses for lung, breast, prostate, colorectal and ovarian cancer was approximately two million. Due to the ever increasing aging population in the United States, it is reasonable to expect that rates of cancer incidence will continue to grow.
Cancer is currently treated using a variety of modalities including surgery, radiation therapy and chemotherapy. The choice of treatment modality will depend upon the type, location and dissemination of the cancer. One of the advantages of surgery and radiation therapy is the ability to control to some extent the impact of the therapy, and thus to limit the toxicity to normal tissues in the body. Chemotherapy is arguably the most appropriate treatment for disseminated cancers such as leukemia and lymphoma as well as metastases. Chemotherapy is generally administered systemically and thus toxicity to normal tissues is a major concern. Not all tumors, however, respond to chemotherapeutic agents and others, although initially responsive to chemotherapeutic agents, may develop resistance. As a result, the search for effective anti-cancer drugs has intensified in an effort to find even more effective agents with less non-specific toxicity.
Recently, much emphasis has been placed on the use of immunotherapy for the treatment and prevention of cancer and other disorders, including infectious disease. Immunotherapy provides the cell specificity that other treatment modalities lack. Methods for enhancing the efficacy of immune based therapies would be beneficial.